1. Field of the Invention
The present invention is directed to a caching method and a caching system and more particularly, to a caching method and a caching system applied in an electronic apparatus having dual disks.
2. Description of Related Art
With the development of the semiconductor technology, capacity of a memory has dramatically increased, and a flash memory is particularly suitable to be used in a portable electronic apparatus for having characteristics, such as non-volatility, low power consumption, or small volume. Therefore, in recent years, a NAND flash memory is gradually used as a storage medium of a solid-state drive (SSD) in considering the volume.
The special features of the SSD lie in replacing the mechanical structure of a hard disk drive (HDD) by utilizing the characteristics of flash memory and performing data accesses by writing and erasing memory blocks. Thus, the efficiency of reading from and writing into a storage apparatus may be significantly improved. Comparing with the traditional storage apparatus, the SSD has advantages, such as low power consumption, shock resistance, low temperature resistance and high stability. Under the consideration of volume, the SSD has gradually become the main data storage apparatus adopted by the portable electronic apparatus.
However, due to the expensive price, a capacity of the SSD capable of being equipped by a consumer electronics product in the market is quite limited. Thus, a dual-disk system composed of a HDD with a high capacity and a SSD with a small capacity has gradually become popular. Therein, the main data accesses are still from the HDD, and the SSD is used as a “cache space” and a “data storage region in a sleep mode”. Accordingly, on one hand, an average data access speed of a PC platform is dramatically improved, while on the other hand, the time of resuming from the sleep mode is effectively shortened. In order to effectively use the small-capacity SSD, it is necessary to design a dual-disk system capable of being implemented and has high efficiency according to the features of the currently existing operation systems.